1. Field of the Invention
The present invention relates to a speckle reduction system, more specifically to a spatial optic modulating system with speckle reduction and a method thereof.
2. Background Art
The conventional optic system is configured to allow mirrors and lenses to be assembled on a large and heavy optical bench by using corresponding implements. In order to improve the efficiency of the optic system, it is required to precisely place an optic axis, a reflecting angle and a reflecting side by using a precise stage.
To solve the problem, there has been an attempt to make the optical system smaller, and such technology used for this attempt is referred to as a micro electro mechanical system (MEMS) or a micro electro mechanical device. Particularly, if the micromachining technology, which is one of the MEMS technologies, is used, not only optical devices having a smaller size than 1 mm but also micro optical systems can be realized.
The micro optical system is employed and applied in information communication apparatuses, information displays and recording apparatuses, due to its quick response, little loss, and integration and digital capabilities. For example, micro optical parts, such as micro-mirrors, micro-lenses and optical fiber holders, can be applied to a data storage device, a large display device, an optical communication device and adaptive optics.
Unlike the conventional large-sized projection systems, there has been a demand for compact-sized, inexpensive optical systems. As a result, devices that display a large-sized image by using a micro-mirror in order to improve the conventional projection system and to display a clearer image, have been manufactured and introduced in the market.
An optical modulator, in particular, including a micro-mirror refers to a circuit or an apparatus loading a signal in the light in a transmitter by using optical fibers or a free space of an optical frequency band as a transmission medium. The optical modulator is used for various fields such as optical memory, optical display, printer, optical interconnection and hologram. Currently, studies on display apparatuses using the optical modulator are actively in progress.
However, in the case of projecting an image to a screen by using the micro-mirror, a speckle, in which the brightness and the darkness are repeated, is generated due to the interference of the projected light. This speckle can cause an unclear image to form on the screen.
To reduce or remove the speckle, the conventional method generates N multiple speckles by regularly moving the screen, to which the image is projected, and offset the uncorrelation of the generated N multiple speckles with one another. Here, N is a natural number.
Beside that, the method of adding an optical device for reducing the speckle to the image system has been suggested. The speckle can be reduced or removed by allowing the optical device for deducing the speckle, which is located on a projecting path of the system, to change the phase of a modulated or projected image.
An apparatus for removing the speckle by mounting a wavefront modulator between a light modulator and a projection/scanning apparatus, which reflects an image to a screen, has also been suggested. However, there is the problem that these apparatuses are large and complex. This is because not only a first image system but also a second image system is required to project an image, which makes it impossible to be used in a compact-sized mobile communication terminal, such as a cellular phone, the portability of which is imperative.